Cavendish, now racing for Omega Pharma Quickstep, got the ideal lead-out from Alessandro Petacchi and moved to the head of the bunch after the peloton caught the breakaway riders with 1km to go, setting up a breakneck finale.

The Manxman burst clear to beat Elia Viviani, winner of the opening stage, and Steele Von Hoff for the stage win. Viviani almost toppled Von Hoff as they crossed the line, so close was the race for second.

The hilly 188.4km route between Stoke-on-Trent to LLanberis in Wales saw Wiggins' lead come under threat as an 11-strong breakaway opened up a four-minute gap before the midpoint of the stage, threatening the former Tour de France champion's slender lead at the top of the general classification.

The gap gradually began to fall, but even with just 20km to go the Team Sky leader's grip on the gold jersey looked anything but secure. At that point Team Sky took the initiative at the front of the peloton to bridge the 1:55 gap, Josh Edmonson and Bernhard Eisel working tirelessly for Wiggins and second-placed Ian Stannard.

With 10km to go Jack Bauer, who finished third in yesterday's time trial, tried to bridge the gap alone but was c aught once more with 5km to go and the leaders being caught rapidly. Each in turn attempted to go it alone at the front in the final 3km, but time and again they were reeled in by others in the breakaway, and in fighting among themselves they allowed the chasing pack to catch them in the final 1000m.

"Alessandro brought me up in perfect position," Cavendish said. "The Bardiani guys went, I jumped on to them, Pelucchi went and I jumped on to him. It was a fast finish."

"Everyone was still burning in the legs from the climb but I am really happy," he added. "It made it quite dangerous catching the breakaway in the last kilometre. That creates carnage."

Stage Four result

1. Mark Cavendish (GB) Omega Pharma QuickStep 4:45:02
2. Elia Viviani (ITA) Cannondale Pro Cycling at same time
3. Steele Von Hoff (AUS) Garmin-Sharp at same time
4. Matteo Pelucchi (ITA) IAM Cycling at same time
5. Jose Joaquin Rojas Gil (ESP) Movistar Team at same time
6. Owain Doull (GB) Great Britain at same time
7. Evaldas Siskevicius (LTU) Sojasun at same time
8. Scott Thwaites (GB) Team NetApp-Endura at same time
9. Chris Opie (GB) Team UK Youth at same time
10. Sam Bennett (IRL) An Post-Chainreaction at same time